1. Do a disk cleanup on the D drive - All Programs/Accessories/System
Tools. Make sure you select More Options/System Restore/Cleanup.
You should do this regularly. I have assigned a keyboard shortcut
(CTRL-C) to this.
2. Delete the unwanted stuff on your D drive. Invest in DVDRWs
(rewritable DVD discs) and transfer your data to those discs.
3. Structure your folders and subfolders in the D drive to more easily
identify what files you need and what you don't.
4. Get a bigger D drive.